Mitsubishi Electric Corp has announced plans to manufacture cellular car telephones in the US and intends to build up production there quickly so as to become one of the top three manufacturers: output, at the Georgia plant of Mitsubishi Consumer Electronics Inc, is initially set at 5,000 sets a month, for sale under both the Mitsubishi and the Diamond Tel brand names; reason for the enthusiasm is that there are already more than 1m car telephone users in the US, 10 times as many as in Japan; Motorola is the US market leader.